Introduction to Solidity Programming 2025

Introduction to Solidity Programming 2025: A Beginner-Friendly Guide with Real-Life Examples

What is Solidity?

Imagine you are building a vending machine that automatically dispenses snacks when the correct amount is inserted. Solidity is like the software that runs this vending machine, ensuring that everything works as programmed without human intervention.

Solidity is a high-level, contract-based programming language used to develop smart contracts on the Ethereum blockchain. Smart contracts are self-executing agreements that automatically perform actions when predefined conditions are met.

Now, let’s explore Solidity step by step with real-life analogies to make it easy to understand.

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1. Basics of Solidity

Solidity is similar to a structured set of rules that define how blockchain-based applications function. Here are some key basics:

• Variables: Just like you store contacts in your phone, Solidity stores data using variables.
• Functions: Similar to buttons on a washing machine, functions perform specific actions when triggered.
• Data Types: Just as a school maintains student names, ages, and grades, Solidity handles numbers, texts, and addresses efficiently.

Example Code

pragma solidity ^0.8.0;
contract Example {
    uint public number;
    function setNumber(uint _number) public {
        number = _number;
    }
}

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Importance and Uses of Solidity

Solidity is essential because it allows developers to create smart contracts, which automate various tasks on the blockchain. These contracts are widely used in different industries, such as:

• Finance: Smart contracts enable decentralized finance (DeFi) applications, including lending platforms and decentralized exchanges.
• Gaming: Blockchain-based games use smart contracts to ensure fair play and true ownership of in-game assets.
• Supply Chain Management: Companies track the journey of products from manufacture to delivery.
• Healthcare: Secure storage and sharing of patient records.
• Real Estate: Buying and selling properties without intermediaries.

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Functions in Solidity

Functions define the operations a smart contract can execute.

Example: Consider a banking app where you check your balance, deposit money, and transfer funds. Solidity functions work in the same way:

• Setter functions: Updating your address in an online form.
• Getter functions: Checking your account balance.
• Modifier functions: Applying a coupon code in an online store before checkout.

Function Syntax Example:

function getBalance() public view returns (uint) {
    return balance;
}

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Working of Solidity

Solidity operates in a structured manner, following a step-by-step process to execute smart contracts. Below is a detailed breakdown of its working:

Step 1: Writing the Smart Contract

Developers write Solidity code using specific functions, variables, and logic. The code defines the rules that the smart contract must follow.

Step 2: Compilation

Before deployment, the Solidity contract is compiled into bytecode using the Solidity compiler (Solc). The compiled code is optimized for execution in the Ethereum Virtual Machine (EVM).

Step 3: Deployment on Blockchain

The compiled contract is deployed onto the Ethereum blockchain, making it accessible to users and other smart contracts. Each contract is assigned a unique address.

Step 4: Execution by Ethereum Virtual Machine (EVM)

Once deployed, the Ethereum Virtual Machine (EVM) executes the smart contract. The EVM ensures that the contract follows predefined rules without external interference.

Step 5: User Interaction

Users interact with the smart contract by sending transactions. These transactions call specific contract functions, such as transferring tokens, updating records, or verifying identities.

Step 6: Updating Blockchain Data

When a contract function is executed, it updates the blockchain. Since blockchain records are immutable, the updated data is permanently stored and cannot be changed.

Step 7: Gas Fees

Each contract execution requires computational resources, which are paid for using gas fees. The more complex a contract, the higher the gas fees.

Diagram Representation of Solidity Workflow:

 User → Writes Solidity Code → Compiler (Solc) → Deploys on Blockchain → EVM Execution → User Interaction → Blockchain Update → Gas Fee Calculation

Example of Contract Deployment and Execution:

pragma solidity ^0.8.0;
contract SimpleStorage {
    uint storedData;

    function set(uint x) public {
        storedData = x;
    }
    
    function get() public view returns (uint) {
        return storedData;
    }
}

In this example:

1. A user deploys SimpleStorage to the blockchain.
2. The set() function is called to store a number.
3. The get() function retrieves the stored value.
4. The updated value is recorded permanently.

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5. Visibility and Activity Qualifiers

Imagine a bank account with different access levels:

• Public: Anyone can check your balance.
• Private: Only you can check your account.
• Internal: Family members (within the same contract) can access.
• External: Special permission required from an outside system.

Example Code

contract VisibilityExample {
    uint private secretData;
    uint public publicData;
}

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Address and Address Payable

Think of an address like a home address or an email ID, while payable is like a credit card that allows transactions.

address owner;
address payable wallet;

A payable address is used when transferring funds between Ethereum accounts.

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Bytes and Enums

• Bytes: Like file storage where images and documents are stored in bytes.
• Enums: Like choosing modes in a washing machine – wash, rinse, or dry.

enum Status { Active, Inactive, Suspended }

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Fixed and Dynamic Arrays

Arrays in Solidity are like a list of grocery items.

• Fixed Arrays: A to-do list with a set number of items.
• Dynamic Arrays: A shopping list that grows as you add more items.

uint[5] fixedArray;
uint[] dynamicArray;

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Special Arrays – Bytes and Strings

• Bytes: Like a compressed zip file storing multiple elements efficiently.
• Strings: Like a text message containing words and characters.

bytes32 data = "Blockchain";
string text = "Hello, Solidity!";

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Structs: Grouping Related Data

A struct is like a contact card that contains multiple details such as name, phone number, and address.

struct Person {
    string name;
    uint age;
}

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Mapping: Key-Value Pair Storage

Mappings work like a phonebook where each name (key) is associated with a number (value).

mapping(address => uint) public balances;

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Advantages of Solidity

1. Automated Execution: Reduces human intervention.
2. Security: Immutable contracts prevent tampering.
3. Transparency: Open-source, anyone can verify.
4. Decentralization: No central authority controls transactions.
5. Fast Transactions: Smart contracts execute instantly.

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Disadvantages of Solidity

1. Complexity: Beginners may find it hard to grasp.
2. Gas Fees: Execution requires Ethereum gas fees.
3. Irreversibility: Mistakes in smart contracts cannot be undone.
4. Security Risks: Bugs in contracts can lead to hacks.
5. Limited Upgradability: Once deployed, modifying contracts is difficult.

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FAQs on Solidity Programming

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Summary

Solidity is a powerful language for building decentralized applications on Ethereum. It operates with variables, functions, arrays, structs, and mappings to create efficient smart contracts. Solidity follows a structured working process, from writing and compiling code to deploying it on the blockchain. While Solidity offers numerous benefits, it also has challenges such as gas fees and complexity. Understanding its core concepts is essential for writing secure and efficient blockchain applications.

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